With Murska (murska.csc.fi) the users are able to run parallel jobs up to 128 processor cores without restrictions. However, bigger parallel jobs than 128 processors require that scalability tests are passed acceptably. One can apply for a temporary scalability permit from address helpdesk@csc.fi. The user has one calendar month time to run the tests and send the results back to scalability support.
The scalability tests are run by using the mpirun command and they should be run though the LSF-SLURM batch job scheduler. For more details and for examples of batch job scripts see:
The program runtime is detected with the time command (which is used in batch job file):
time mpirun -srun ./mpitestThe time command is needed for scalability tests only. In Murska, the time command writes the timing statistics to "system error message output" file, which is defined in a batch job file with option: #BSUB -e
To provide proper data about the scalability of the program, do the following steps:
- Generate one or more test runs which correspond your production runs well, but are clearly shorter in time.
- Run these batch jobs with Murska using 8, 16, 32, etc., processors up to the wanted number of processors.
- Collect the timing statistics for an array of results.
- Send the data by email to CSC to e-mail address: helpddesk@csc.fi. (Note: Your message is not necessarily responded, unless we need more details.) Please mention, if your results are applicable for other users.
A parallel code has been, in general, judged at CSC to scale well when the speed-up factor is at least 1.5 when the number of processors has been doubled. CSC is also able to provide assistance in the code optimization problems, if needed.
Any possible questions can be sent to the e-mail address:
